FEEDSTOCK CONVERSION FROM BAUXITE TO SGH

Sumitomo Chemical Co., Ltd. (SC) and other Japanese alumina makers committed to quit the ocean-dumping of bauxite residue by 2015 at the 2005 Scientific Group Meeting of the London Convention. In 2006, SC planned to change the feedstock from bauxite to imported Smelter Grade Hydrate (SGH), because we considered that this method (re-precipitating aluminium tri-hydrate
(ATH) from the digested SGH) was the most suitable for the stabilization of the quality of the downstream products. The plan brought concern about the change of the impurities included in ATH and Bayer liquor by feedstock conversion. To confirm it, we built a 1/10,000 scale Bayer pilot plant, operated it for about 2 years and collected many quality data of the products sample before changing the feedstock.

These data showed that re-precipitated ATH from the liquor of digested SGH had the same quality as ATH from bauxite. We obtained customer’s approval to change feedstock based on that data.

In May 2010, we executed feedstock conversion, and confirmed the quality of re-precipitated ATH is the same quality as the one from bauxite. We also confirmed the plant data is the same as the pilot plant. Customers are satisfied with the quality of our products.